ATXN2

ATXN2 and Glaucoma Risk — When an Aging Gene Threatens Vision

Ataxin-2 (ATXN2) encodes an RNA-binding protein best known for its role in spinocerebellar ataxia type 2, a neurodegenerative disorder caused by massive CAG repeat expansions in the gene. But common variants in ATXN2 tell a different story — one that intersects aging biology, RNA metabolism, and the health of the cells that let you see. The rs7137828 variant, sitting in an intron of ATXN2, has been robustly linked to primary open-angle glaucoma (POAG), the most common form of glaucoma and the leading cause of irreversible blindness worldwide.

The landmark 2016 meta-analysis | Cooke Bailey JN et al. Genome-wide association analysis identifies TXNRD2, ATXN2 and FOXC1 as susceptibility loci for primary open-angle glaucoma. Nat Genet. 2016 analyzed 5,990 glaucoma cases and 40,179 controls across U.S., Australian, European, and Singaporean cohorts. It identified rs7137828[T] as a genome-wide significant risk allele (OR=1.17, p=8.73×10⁻¹⁰), and showed that ATXN2 protein is expressed in retinal ganglion cells and the optic nerve head — the exact tissues that degenerate in glaucoma.

The Mechanism

A 2025 functional study | Shi Song Rong et al. ATXN2 loss of function results in glaucoma-related features supporting a role for Ataxin-2 in primary open-angle glaucoma pathogenesis. Vision Res. 2025 used CRISPR-edited zebrafish to establish how ATXN2 influences eye health. Fish lacking functional atxn2 developed reduced eye size, fewer retinal ganglion cells, elevated intraocular pressure (IOP), and impaired visual function — reproducing the hallmarks of human glaucoma in a model organism. Complementation assays confirmed that 14 human ATXN2 missense variants associated with POAG have genuine functional effects on the gene, pointing to a loss-of-function mechanism.

At the molecular level, ataxin-2 is a multifunctional RNA-binding protein. It regulates
mRNA translation via the PI3K/mTOR pathway | Lastres-Becker I et al. Nat Commun. 2016,
assembles into stress granules during cellular stress, and modulates protein synthesis in response to nutrient deprivation. In retinal ganglion cells, which must maintain long axons all the way to the brain's lateral geniculate nucleus, this RNA metabolism role may be critical for sustaining cellular health across decades. A variant that subtly impairs ataxin-2 function — or alters its expression in relevant tissues — likely reduces the resilience of these non-regenerating neurons over time.

The Evidence

The glaucoma association for rs7137828 meets the highest standards of genetic evidence. The discovery OR of 1.17 per T allele (95% CI approximately 1.12–1.22) was replicated across multiple independent populations including European-American, Australian, and Singaporean cohorts.

A 2023 Brazilian replication | Rodrigues TAR et al. Ophthalmic Genet. 2023 confirmed the finding in 506 POAG cases and 501 controls: TT homozygotes faced nearly double the risk compared to CC homozygotes (OR=1.717, 95% CI 1.169–2.535, p=0.006). Even CT heterozygotes showed measurable differences in vertical cup-to-disk ratio (VCDR), a structural biomarker of glaucomatous damage, suggesting a dose-dependent effect on optic nerve morphology.

The variant's placement in the 12q24 chromosomal region is also notable for its connections to broader aging biology.
An informed GWAS for exceptional longevity | Fortney K et al. Genome-Wide Scan Informed by Age-Related Disease Identifies Loci for Exceptional Human Longevity. PLoS Genet. 2015 identified the SH2B3/ATXN2 locus as one of just four loci replicated at FDR < 5% for extreme longevity across centenarian cohorts, and noted that ATXN2's Drosophila ortholog extends lifespan when manipulated. The neighboring SH2B3 gene encodes LNK, a signaling adaptor that modulates cytokine and insulin receptor pathways — underscoring how this chromosomal region sits at the crossroads of immune regulation, metabolic aging, and now ocular health.

Practical Actions

POAG is particularly insidious because it causes painless, slow loss of peripheral vision that most people don't notice until substantial damage has occurred. The T allele adds a modest but real increment of lifetime risk on top of other glaucoma risk factors (age, elevated IOP, thin corneas, family history, African ancestry).

The most actionable implication is earlier and more vigilant eye pressure monitoring. Standard guidelines recommend comprehensive eye exams including IOP measurement every 1–2 years from age 40, but carriers of one or two T alleles — especially if combined with other risk factors — have reason to start earlier (age 35) and to specifically request optic nerve imaging (OCT). Caught early, glaucoma is highly manageable with topical medications or laser therapy; caught late, the vision loss is permanent.

Intraocular pressure is also modifiable: aerobic exercise consistently lowers IOP | Passo MS et al. Arch Ophthalmol. 1991, and caffeine consumption acutely raises it. For carriers seeking to reduce modifiable risk, regular aerobic activity and monitoring of coffee intake may offer meaningful benefit.

Interactions

The rs7137828 ATXN2 variant sits within the 12q24 locus alongside rs3184504 in SH2B3, which encodes the LNK signaling adaptor and is the primary variant associated with longevity and cardiovascular protection at this locus. The two genes are distinct but biologically intertwined: SH2B3/LNK regulates hematopoietic and immune signaling, while ATXN2 regulates RNA metabolism and protein synthesis. Both contribute to the pleiotropic disease associations of 12q24 — covering autoimmune, cardiovascular, neurodegenerative, and now ocular conditions. Individuals carrying risk alleles at both rs7137828 (ATXN2, glaucoma) and rs3184504 (SH2B3, cardiovascular/longevity) may warrant particularly comprehensive health monitoring across multiple organ systems, though formal combined-risk studies have not been published.

ATXN2 also intersects with TDP-43 biology: intermediate CAG repeat expansions in ATXN2 (27–33 repeats, not yet disease-causing on their own) increase the risk of ALS by stabilizing TDP-43 aggregates. The common rs7137828 variant does not affect repeat length, but highlights ATXN2's biological proximity to RNA metabolism pathways that span glaucoma, neurodegeneration, and aging.